JP2001357725A - Conductive elastic body and image forming device using it as well as manufacturing method of conductive elastic body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive elastic body which is appropriate as means for static charging, development and transfer in an electro-photographic process, and provide its manufacturing method and an image forming device using the conductive elastic body. SOLUTION: This is a conductive elastic body consisting of at least a substrate and an elastic body having not less than two layers. By coating a elastic layer on the surface layer of the conductive elastic body consisting of the substrate and the inner elastic body, the average cell diameter of the surface layer of the inner elastic body becomes smaller not less than 10% in comparison with that before coating the coating elastic layer, or the thickness of the inner elastic body becomes thinner 5 to 10% in comparison with that before coating the coated elastic layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a general conductive elastic material used in an electrophotographic apparatus and the like, and more particularly to, for example, a copier (registered trademark) used in contact with an image carrier in a laser printer. The present invention relates to a conductive elastic body and a method for covering the conductive elastic body.

[0002]

2. Description of the Related Art In an electrophotographic system, a high voltage is conventionally applied to a metal wire, and a photosensitive member is charged or transferred by a corona generated. However, in this corona charging method, ozone or NOx
Since the surface of the photoreceptor is deteriorated by corona products such as those described above, there is a problem not only in image quality such as image white spots and black stripes but also in office environment. Therefore, as a method that does not generate ozone, NOx, and the like, a method of charging and transferring by contacting a conductive elastic body with a photoreceptor or the like has been proposed.

In an electrophotographic image forming apparatus, a DC voltage is applied to a conductive elastic body provided opposite to the image carrier as a charging means for charging the image carrier to form a latent image on the image carrier. A process of applying an AC voltage to perform contact charging, a developing process of supplying toner to an electrostatic latent image on the image carrier to visualize the toner, and transferring a toner image formed on the image carrier to a transfer material As a means for performing this, there is a process of applying a voltage of several hundred V to 2 kV from the back side of the transfer material to a conductive elastic body attached to the image carrier to perform contact transfer.

[0004] The conductive elastic body used in these is used by abutting or pressing against an opposing member such as a photoreceptor. Therefore, in consideration of the long life of the conductive elastic body, the conductive elastic body has a sufficient restoring force (a so-called “resilient member”). C-set is prevented) The hardness of the conductive elastic body must be increased. In particular, when a conductive elastic body is used for the transfer means, a large pressing force is required to sufficiently secure a transfer nip between the opposing member and the conductive elastic body. Under the condition of solid rubber disclosed in Japanese Patent Application Laid-Open No. 10-171274, a total pressure of 3 to 10 kg is required, so that friction between the opposing member such as the photoconductor and the like causes the opposing member such as the photoconductor to be frictionally applied. Wear and deterioration will occur.

In recent years, as the quality of the facing member such as a photoconductor has been reduced in thickness due to the improvement in image quality, abrasion deterioration of the facing member such as the photoconductor is a serious disadvantage. In order to prevent such a drawback, a foamed elastic body in which the hardness of the conductive elastic body is reduced so as not to cause C-set may be used.
It is very difficult to achieve precise roundness, cylindricity, straightness, and flatness. Not only does the cell on the foamed elastic body adversely affect the latent image / toner image, but also the foamed elastic body due to dielectric breakdown Oxidation and composition change of the surface layer, and residual toner remaining on the image carrier such as the photoreceptor are transferred to the foamed elastic body and enter the cells of the foamed elastic body surface layer to make cleaning difficult, and after long-term use, Be contaminated. As a result, stains on the surface of the image bearing member, charging, phenomenon, transfer failure, stains on the back of the recording paper,
Problems such as an increase in the volume resistivity of the conductive elastic body occur.

Accordingly, it is necessary to clean the residual toner transferred to the conductive elastic body. In this case, a method of cleaning the surface of the foamed elastic body with a blade, a fur brush, or the like, or by applying a predetermined voltage, is used. A method of returning the toner to the image carrier has been devised,
Not enough yet. Further, the foamed elastic body constituting the conductive elastic body is an organic synthetic polymer, and at present, it is difficult to recycle it as a raw material. As a countermeasure against these problems, a conductive elastic body in which a coating layer is provided on a surface layer of a foamed elastic body in consideration of the toner releasability, abrasion resistance, and durability has been proposed. However, it is very difficult to adhere the foamed elastic body to the coating layer, and problems such as peeling and lifting occur between them.

As a countermeasure against these problems, there is a method of bonding using an adhesive, but if a special adhesive is used,
The resistance of the adhesive may cause a change in the overall volume resistivity or a local change in the volume resistivity. Bonding by chemical reaction between polymers is also possible without using a special adhesive, but the change in the overall volume resistivity due to the composition change at the bonding part at that time, the local volume resistivity change, In some cases, a change in hardness or the like may be caused. Further, not only a complicated technique is required in the manufacturing process, but also the cost is extremely increased.

Further, as a countermeasure against the above problem, Japanese Patent Application Laid-Open
JP-A-228187 proposes a means for heating a coating layer to fuse it with a foamed elastic body. However, in this case, since the coating layer is fused, it is difficult to easily remove the coating layer, and a change in the resistance value due to a change in the composition on the fusion surface occurs.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has been made in consideration of the above-mentioned problems of the prior art. It is an object of the present invention to provide a method and an image forming apparatus using the conductive elastic body.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a conductive elastic body composed of at least a substrate and two or more layers of an elastic body has a conductive elastic body composed of a base and an internal elastic body. Covering the surface layer of the elastic body with the covering elastic layer,
The present inventors have found that a conductive elastic body satisfying the above-mentioned problems can be obtained by controlling the surface layer average cell diameter of the internal elastic body, the thickness of the internal elastic body, and the like, and completed the present invention. Further, in producing a conductive elastic body composed of at least two layers of elastic bodies, a coating layer and an internal elastic body are used by using an expansion force generated by foaming and curing of an unfoamed elastic body as a force due to expansion of the internal elastic body. It has been found that an excellent conductive elastic body can be obtained by bringing these into close contact with each other, and the present invention has been completed.

That is, the present invention provides at least a substrate and 2
A conductive elastic body composed of an elastic body having at least two layers,
By coating the surface layer of the conductive elastic body composed of the base and the internal elastic body with the coating elastic layer, the average cell diameter of the surface layer of the internal elastic body is 10 times smaller than that before the coating of the coating elastic layer.
% Or less.

The present invention also relates to a conductive elastic body comprising at least a base and two or more elastic bodies, wherein a covering elastic body is provided on a surface of the conductive elastic body comprising a base and an internal elastic body. The present invention relates to a conductive elastic body characterized in that the thickness of the internal elastic body is reduced by 5 to 20% by coating, as compared to before the covering elastic layer is coated.

Further, the present invention relates to a method for producing a conductive elastic body comprising at least two layers of elastic bodies, wherein the expansion caused by the expansion and hardening of the unfoamed elastic body as a force due to the expansion of the internal elastic body. The present invention relates to a method for producing a conductive elastic body, which comprises bringing a coating layer and an internal elastic body into close contact with each other using force.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a schematic sectional view of the image forming apparatus of the present invention. The image forming apparatus is used as an output device of a computer, but can also be used as a word processor, a facsimile printing unit, a digital copier printing unit, and the like. In the image forming apparatus of the present invention, an image forming method for an image carrier necessary for recording an image on an image forming body includes:
Various image forming principles can be used in addition to the Carlson process and the backside exposure method, and there is no particular limitation. This embodiment is an example of an image forming apparatus using the Carlson process.

The image forming apparatus shown in FIG. 8 mainly comprises an image forming section 10 for forming an image and a supply device 30 for supplying paper P to the image forming section 10. The image forming unit 10 includes a photosensitive drum 11 as an image carrier having a photosensitive layer disposed on an aluminum tube, a charging device 12 disposed around the photosensitive drum 11 in this order, and an exposure device (laser unit) 13. , A developing device 14, a transfer device 15, a charge removing device (a charge removing lamp) 16, and a fixing device 17.

The charging device 12 includes a charging conductive member (charging means) 18 for applying a uniform charge to the surface of the photosensitive drum 11 and a charging power supply for supplying a potential to the charging conductive member 18. 19 is provided. The laser unit 13 irradiates a laser to the charged surface of the photosensitive drum 11 in accordance with image data, and
An electrostatic latent image composed of a charge pattern is formed on the surface of the photosensitive drum 1. A developing conductive member (developing means) 21 for supplying a toner 50 as a developer to the electrostatic latent image formed by exposure of the laser unit 13 to form a toner image; A developing power source 22 for supplying a developing voltage to the developing conductive member 21 is provided. The transfer device includes a transfer conductive member (transfer unit) 23 that presses the sheet P against the photoconductor drum 11 and transfers the toner image formed on the photoconductor drum 11 to the sheet P; 2
3 is provided with a transfer power supply 24 for supplying a transfer voltage. The static elimination lamp 16 is composed of a plurality of LEDs.
The surface of the photosensitive drum 11 is irradiated with light to neutralize the charge remaining on the surface of the photosensitive drum 11 to eliminate the charge.

The paper feeder 30 includes a cassette 31 for storing the paper P, a pickup roller 32 for feeding the paper P from the cassette 31, a paper feed guide 33 for guiding the supplied paper P, And a pair of registration rollers 34 that convey at a speed of. Also, the paper feeding device 3
Reference numeral 0 denotes a paper feed sensor (not shown) that detects that the paper P has been supplied.

The above-mentioned pickup roller 32, charged conductive member 18, developing conductive member 21, transfer conductive member 2
3 and the photosensitive drum 11 are driven to rotate by a driving device (not shown). These rotation drives are appropriately controlled at a predetermined timing by a process control unit (not shown). On the paper output side of the paper P of the image forming unit 10, a paper discharge roller 41 for discharging the paper P to the outside of the apparatus and a paper discharge tray 42 for holding the discharged paper P are arranged. In the image forming apparatus having the above configuration, the conductive elastic body according to the present invention can be suitably used for the charged conductive member 18, the developing conductive member 21, the transfer conductive member 23, and the like.

Examples of the conductive elastic body having a roller shape, which is one embodiment of the conductive elastic body of the present invention, include those having structures as exemplified in FIGS.
In FIGS. 1 and 2, a base 1 is made of, for example, a so-called “core metal” made of iron, aluminum, SUS, brass, or the like, and further includes, for example, a core made of a thermoplastic resin and / or a thermosetting resin. A core formed of a conductive resin molded product obtained by plating the surface thereof, a thermoplastic resin and / or a thermosetting resin, and a conductive carbon black or a metal powder as a conductivity-imparting agent. And any material selected from plastics, metals, ceramics, and the like, such as a core made of a combination of the above.

The conductive elastic body has an internal elastic body 2 mainly composed of, for example, non-polar rubber such as ethylene-propylene-diene copolymer rubber (EPDM), and has a surface layer (that is, an image bearing member and the like). The contacting portion) is covered with a coating elastic layer 3 made of, for example, a flexible synthetic resin such as a nonpolar polyethylene resin having conductivity.

In the blade-shaped embodiment, as shown in FIG. 3, the base 1, the internal elastic body 2 and the coating elastic layer 3 can be formed in a flat plate shape.

In each of the embodiments shown in FIGS. 1 and 3, the average cell diameter of the surface layer of the inner elastic body 2 is reduced by 10% or more as compared with that before the coating of the coating elastic layer. 90% or less. 1 and 3, the state of the cell 5 is schematically shown. Here, the “cell” refers to bubbles generated during the production of the elastic body, specifically, bubbles generated when the polymer resin as a raw material is mixed and bubbles generated during the heat treatment are left in the completely formed body. It was done. In the present invention, the average cell diameter of the surface layer of the internal elastic body 2 is reduced by 10% or more, preferably about 10 to 35%, more preferably about 15 to 25% as compared to before the coating of the coating elastic layer. It is more preferable that the size be smaller. The internal elastic body 2 and the coating elastic layer 3 are mixed with a conductive filler 4 such as ceramic fine powder which is sintered and pulverized at a high temperature, for example, to achieve medium resistance and to adjust the resistance value. .

FIGS. 4 and 5 show another embodiment of the conductive elastic body of the present invention. In each of the embodiments, the thickness of the internal elastic body is 5 to 5 times as compared with that before the covering elastic layer is coated. 20% thinner. FIG. 4 shows an example of a roller shape, and FIG. 5 shows an example of a blade shape.

As the internal elastic body 2 in the conductive elastic body of the present invention, for example, ethylene-propylene diene polymer (EPDM), butadiene rubber, styrene-butadiene rubber (SBR), high styrene rubber, isoprene rubber, butyl rubber, Non-polar estramers such as silicone rubber and natural rubber (NR), polar estramers such as nitrile butadiene rubber, chloroprene rubber, fluoro rubber, nitrile rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber, norbornene rubber, polystyrene, poly- Non-polar materials such as α-methylstyrene, styrene-butadiene copolymer, styrene-maleic acid copolymer, low molecular weight polyethylene, low molecular weight polypropylene, phenolic resin, silicone resin, xylene resin, and copolymers and mixtures thereof Resin, chloropolystyrene, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene- Butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylate copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate) Styrene-based resins (including styrene or styrene-substituted copolymers) such as copolymers, styrene-phenyl methacrylate copolymer, styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, and the like. Homopolymer or copolymer), vinyl chloride Fat, styrene - vinyl acetate copolymer, rosin-modified maleic acid resin,
Epoxy resin, polyester resin, ionomer resin,
Polyurethane resins, ketone resins, ethylene-ethyl acrylate copolymers, fluorine resins, polycarbonate resins, polyamide resins, vinyl butyral resins, and polar resins such as copolymers and mixtures thereof can be mentioned. From the viewpoint of suppressing the accompanying volume resistivity fluctuation and lowering the hardness, ethylene-propylene diene polymer (EPDM), butadiene rubber, styrene-butadiene rubber (SBR), high styrene rubber, isoprene rubber, butyl rubber, silicon rubber, natural rubber Non-polar elastomers such as rubber (NR) are most preferred.

Examples of the coating elastic layer 3 include polystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-maleic acid copolymer, low molecular weight polyethylene, low molecular weight polypropylene, phenol resin, silicone resin, Non-polar resins such as xylene resins and their copolymers and mixtures, chloropolystyrene, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-acrylate copolymer (styrene-methyl acrylate) Copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer ( Styrene-methyl methacrylate copolymer Styrene-based resins (styrene or styrene-ethyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-methyl methyl acrylate copolymer, styrene-acrylonitrile-acrylate copolymer, etc. (Homopolymer or copolymer containing a styrene substituent), vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic resin, epoxy resin, polyester resin, ionomer resin, polyurethane resin, ketone resin, ethylene-ethyl Acrylic resins, fluorinated resins, polycarbonates, polyamide resins, polar vinyl resins such as vinyl butyral resins and their copolymers and mixtures can be cited, but from the effect of suppressing volume resistivity fluctuations due to environmental changes, Polystyrene, poly-α-methyl Most preferred are non-polar resins such as tylene, styrene-butadiene copolymer, styrene-maleic acid copolymer, low molecular weight polyethylene, low molecular weight polypropylene, phenolic resin, silicone resin, xylene resin, and copolymers and mixtures thereof. .

In the present invention, it is preferable that a conductive filler 4 is blended in the internal elastic body 2 and the coating elastic layer 3, and the conductive filler is, for example, a quaternary ammonium salt-containing polymethyl methacrylate. Conductive resin such as polyvinylaniline, polyvinylpyrrole, polydiacetylene and polyethyleneimine; conductive particles such as carbon, aluminum, nickel and the like; resin such as urethane, polyester, vinyl acetate-vinyl chloride copolymer and polymethyl methacrylate Conductive particles dispersed resin, metal powder such as aluminum, nickel and stainless steel, conductive such as titanium oxide, tin oxide, barium sulfate, aluminum oxide, strontium titanate, magnesium oxide, silicon oxide, silicon carbide, nitrogen silicon, etc. Inorganic particles, These whiskers and mica have been subjected to surface treatment with tin oxide, antimony oxide, carbon, etc. as necessary, or electronic conductive fillers such as carbon black (channel black, furnace black, acetylene black), and perchlorine. Lithium oxide,
Sodium perchlorate, lauryl trimethyl ammonium chloride replaced with salt like calcium perchlorate,
Stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, modified aliphatic dimethylethylammonium ethosulfate, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, tetrabutylammonium borofluoride, Quaternary ammonium salts such as tetraethylammonium borofluoride and tetrabutylammonium, ionic conductive fillers such as alkylsulfonates, phosphates and perchlorates, and polycrystalline sintering at high temperatures Examples include ceramic fine powder obtained by pulverizing the body.
Ceramic fine powder obtained by pulverizing a polycrystalline sintered body sintered at a high temperature is preferable.

Examples of the ceramic fine powder include SiO ₂ , MgO, Al ₂ O ₃ , CaO, PbO, F
e ₂ O ₃ , BaO, TiO ₂ , ZnO, ZrO ₂ , SrO,
Mullite comprising components such as Li ₂ O, corundum, cristobalite, sapphirine, cordierite, forsterite, spinel, barium titanate (BaTi
O ₃ ), magnesium titanate (MgTiO ₃ ), calcium titanate (CaTiO ₃ ), strontium titanate (SrTiO ₃ ), lanthanum titanate, zinc titanate, bismuth titanate, PbTiO ₃ , KNbO ₃ , Mg
_{TiO 3 -CaTiO 3, BaO · 4TiO} 2 -TiO 2,
_{2MgO · SiO 2 -SrO-BaO-} TiO 2, BaT
_{iO 3 -Nd 2 O 3 -TiO 2} , PbTiO 3 -PbZr
O ₃ , BaTiO ₃ —SrTiO ₃ —La ₂ O ₃ —Ti
O ₂ , SrTiO ₃ —CaTiO ₃ —Bi ₂ O ₃ —TiO _{2 and the} like. Since the fine powder of these sintered bodies has been heat-treated at a high temperature of 1000 ° C. or more, it is chemically stable, does not cause a chemical reaction with other substances, and has an electronic conductive filler such as carbon black or a second conductive material. Unlike ionic conductive fillers such as quaternary ammonium salts and lithium perchlorate, the presence or absence of the polarity of the polymer constituting the internal elastic body 2 and the temperature of the manufacturing process are not selected. When a solid solution is pulverized instead of a polycrystalline sintered body, the preparation is easy, but the chemical stability is insufficient, which is not preferable. Since the particle size of the fine powder can be reduced without limit, it is possible to suppress the variation in the position of the electric resistance of the conductive elastic body mixed with the ceramic fine powder. In addition, by selecting a ceramic fine powder having a large dielectric constant, the electric charge is not charged to the ceramic fine powder.
There is no change in volume resistivity with respect to the applied voltage.
When a titanium oxide unit is used, the dielectric constant is around 100, so that the hardness of the elastic body 2 is increased due to an increase in the amount mixed into the elastic body 2 and the bleeding to the surface of the conductive elastic body is prevented. In addition, the volume resistivity cannot be sufficiently reduced, and a conductive elastic body having a medium resistance cannot be obtained. Therefore, in order to obtain a conductive elastic body having a medium resistance, it is preferable to use a ceramic fine powder having a dielectric constant of 100 or more, and particularly a ceramic fine powder of 200 or more, as a conductive filler. Many ceramic fine powders satisfying this condition include binary or ternary ceramic fine powders containing at least titanium oxide.

As additives other than the conductive filler, for example, a vulcanizing agent, a vulcanization accelerator, a foaming agent, an antioxidant, a reinforcing agent, a filler, and the like may be added as required. It is possible.

As the vulcanizing agent, for example, organic peroxides and the like can be used in addition to sulfur and organic sulfur-containing compounds. Examples of the organic sulfur-containing compound include tetramethylthiuram disulfide. In addition, examples of the organic peroxide include benzoyl peroxide. Of these, it is preferable to use sulfur from the viewpoint that the balance between the vulcanization speed and the foaming speed is improved when foaming is performed together with vulcanization.

As the vulcanization accelerator, for example, inorganic accelerators such as slaked lime, magnesia (MgO) and litharge (PbO), and organic accelerators described below can be used.
Examples of the organic accelerator include thiazole vulcanization accelerators such as 2-mercaptobenzothiazole and N-cyclohexyl-2-benzothiazolesulfene; and aliphatic primary amines such as n-butylamine, tert-butylamine and propylamine. Condensates of 2-mercaptobenzothiazole with 2-mercaptobenzothiazole, oxidative condensates of aliphatic secondary amines such as dicyclohexylamine, pyrrolidine and piperidine with 2-mercaptobenzothiazole, alicyclic primary amine and 2-mercaptobenzothiazole , A sulfenamide-based vulcanization accelerator such as an oxidized condensate of a morpholine compound and 2-mercaptobenzothiazole, tetramethylthiuram monosulfide (TMTM), tetramethylthiuram disulfide (TMTD), tetraethylthiuram Dimonosulf De (TETD), tetrabutyl Chi Raum dimonium ɽ sulfide (TBTD), thiuram vulcanization accelerators such as dipentamethylenethiuram tetrasulfide (DPTT), zinc dimethyldithiocarbamate (ZnM
DC), zinc diethyldithiocarbamate (ZnED
C), dithiocarbamate-based vulcanization accelerators such as zinc di-n-butylcarbamate (ZnBDC) and the like can be used. Further, a vulcanization accelerating aid can be blended, for example, a metal compound such as zinc white, stearic acid,
Fatty acids such as oleic acid and cottonseed fatty acids can be used.

Examples of the foaming agent include water, A.I. I.
B. N. (Azobisisobutyronitrile), A.I. D.
C. A. (Azodicarbonamide) type, D.I. P. T.
(Dinitrosopentamethylenetetramine), T.I. S.
H. (P-toluenesulfonyl hydrazide), O.I.
B. S. H. An organic blowing agent such as (4,4'-oxybisbenzenesulfonyl hydrazide) is used. The amount of the foaming agent is preferably about 5 to 11 parts by weight based on 100 parts by weight of the rubber component of the composition. This is because if the amount is less than 5 parts by weight, the foaming may be insufficient, and if the amount is more than 11 parts by weight, the foaming agent may inhibit vulcanization and vulcanization may be insufficient. When the composition is a foam, flexibility is improved. When this is used as a transfer unit, a sufficient nip between the photoconductor and the transfer unit can be secured, and good image quality can be obtained.

Examples of the antioxidants include imidazoles such as 2-mercaptobenzimidazole, phenyl-α-naphthylamine, N, N′-di-β-naphthyl-p-phenylenediamine, N-phenyl-N′-. Examples include amines such as isopropyl-p-phenylenediamine, and phenols such as di-tert-butyl-p-cresol and styrenated phenol.

As the filler, for example, silica, clay, talc, calcium carbonate, dibasic phosphite (D
LP), basic magnesium carbonate, alumina and the like. The addition of a filler improves the strength of the rubber composition.

The method for producing a conductive elastic body of the present invention will be described by taking a conductive elastic body having a roller shape as an example. First, a ceramic fine powder and / or an ionic conductive filler or an electronic conductive filler are used. And at least one conductive filler 4 obtained by combining at least one of the above and a vulcanizing agent such as hydrogen polysiloxane or sulfur in the presence of the above-mentioned blowing agent, peroxide or platinum catalyst. Dispersed unvulcanized, unfoamed rubber material, for example, open roll,
Kneading is performed using a known rubber kneading device such as a Banbury mixer. At this time, if necessary, additives such as a vulcanization accelerator, a softener, a plasticizer, a reinforcing agent, an antioxidant, and an antistatic agent can be appropriately compounded. The unvulcanized and unfoamed rubber material is molded by a method such as press molding, extrusion molding, or injection molding.

Next, vulcanization / foaming / curing by heat treatment is performed to integrate the unfoamed elastic body and the substrate 1 to obtain the desired internal elastic body 2 having a shape along the inner peripheral surface of the mold. be able to. The base 1 can be supported by the base 1 without increasing the hardness of the internal elastic body 2, and it is possible to prevent a pressure drop due to temporal settling or the like and a reduction in the durable life. The base 1 has a heat resistance temperature of about 220 around its outer periphery.
It is preferable to apply an adhesive at about ° C.

Next, the skin layer formed on the surface of the internal elastic body 2 is polished and ground. Thereby, the elastic body 2
Can be reduced, so that abrasion with the press contact member can be prevented. It is also possible to prevent cracking of the skin layer due to fatigue in advance. From the above steps, a conductive elastic body composed of only the base 1 and the internal elastic body 2 can be manufactured.

Next, a coating elastic layer 3 made of, for example, a flexible synthetic resin or the like is provided on the surface layer of the internal elastic body 2 of the conductive elastic body obtained by the above steps. It is preferable that the resistance of the coating elastic layer is adjusted by doping a ceramic fine powder and / or a conductive filler such as an ionic conductive filler and an electronic conductive filler.

The means for covering the inner elastic body 2 with the covering elastic layer 3 is, for example, expanding and expanding the covering elastic layer with a vacuum plate, inserting the inner elastic body 2 therein, and applying a force for returning to the natural state. A variety of other methods can be used, such as a method in which the coating elastic layer and the internal elastic body are brought into close contact with each other by always adding the coating elastic layer to the internal elastic body 2, or a method in which the coating elastic layer is brought into close contact by utilizing thermal contraction. On this occasion,
An adhesive may be used between the internal elastic body 2 and the coating elastic layer 3, but the coating elastic layer can be easily peeled off at the time of recycling, and the adhesive leaks out to the surface of the conductive elastic body. It is preferable that the elastic body 2 has no adverse effect on the volume resistivity of the conductive elastic body.
Most preferred is a method capable of adhering the coating elastic layer and the coating elastic layer.

Next, a preferred method for producing the conductive elastic body of the present invention will be described in detail by taking a conductive elastic body having a roller shape as an example. First, a schematic view of an apparatus used for manufacturing a conductive elastic body has a shape as shown in FIG.
Here, as the base 1, the internal elastic body 2, and the coating elastic layer 3, any of the above-mentioned materials can be used.

An unfoamed internal elastic body 2 in which additives such as a conductive filler and a foaming agent are mixed and uniformly dispersed is coated on the substrate 1 and the surface thereof is coated with an elastic layer made of a flexible synthetic resin or the like. 3 is set inside the mold 6. On the inner periphery of the mold, a foamed elastic body 7 made of a single cell is integrated with the mold 6 so that an external pressure is applied from the surface of the coating layer. Shrinkage occurs uniformly, and by using an elastic body that is resistant to repeated fatigue, the foamed elastic body 7 can be reused many times.

Next, by performing a heat treatment, vulcanization, foaming, and curing are performed to integrate the foamed internal elastic body 2 and the base 1 into a desired internal elastic body having a shape along the inner peripheral surface of the mold. Body 2 can be obtained. At this time, the foamed elastic body 7 expands due to the applied heat, and a uniform pressure can be applied to the coating layer. Thereby, the adhesion between the foamed elastic body 2 and the substrate 1 becomes strong, and the coating layer can be adhered without using an adhesive or the like. The base 1 can be supported by the base 1 without increasing the hardness of the internal elastic body 2, and it is possible to prevent a pressure drop due to a temporal settling or the like and a reduction in the durable life. Base 1
It is preferable that an adhesive having a heat resistance temperature of about 220 ° C. is applied to the outer periphery.

In the case of the apparatus shown in FIG. 7, a schematic diagram in which the means for applying an external pressure from the surface of the coating layer is based on expansion and contraction of the gas 8 is exemplified, and the basic configuration is the same as that of FIG. . The gas 8 expands due to heat at the time of heat treatment for vulcanizing, foaming and hardening the unfoamed internal elastic body 2, and the tube 9 containing the gas 8 made of a fluororesin also expands,
A uniform pressure can be applied to the coating layer. At this time, it is desirable to use chemically and physically stable nitrogen gas or argon gas. The reason why the fluorine resin is used for the tube 9 is that the tube 9 and the coating elastic layer 3 do not adhere to each other during the heat treatment. If the material of the foamed internal elastic body 2 requires a large amount of heating at the time of the heat treatment and becomes extremely high temperature, the gas 9 expands excessively, and the tube 9 may be damaged, or the internal elastic body 2 Pressure sensor 100 for adjusting the pressure of gas 8 and a pressure adjusting device in order to eliminate inconveniences such as hindering vulcanization / foaming / curing and hindering adhesion between foamed internal elastic body 2 and substrate 1. 90. This makes it possible to release pressure more than necessary. When the temperature during the heat treatment is relatively low and the pressurization due to the expansion of the gas 8 is not sufficient, the temperature of the gas 8 may be increased by the temperature sensor 110 and the temperature control device 80 to obtain a necessary and sufficient pressure. It becomes possible. The operation of temperature, volume, and pressure on the gas is not limited to this, and other means can be used.

In the method of the present invention, the above-mentioned conductive filler which is doped for adjusting the resistance of the coating layer 3 such as the elastic body 2 or the flexible synthetic resin can be used. Optional.

[0044]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Production Example Specifically, it is preferable in terms of work and performance to produce the conductive elastic body by the following method. That is, the desired BaTi
Average particle diameter of 1 μm such as O ₃ or PbTiO ₃ -PbZrO ₃
EPDM, which is a constituent material of the rubber composition part appropriately mixed with the ceramic fine powder, and other additives such as a foaming agent, a vulcanizing agent, a vulcanization accelerator, a softening agent, a plasticizer, a reinforcing agent, an antioxidant, and an antistatic agent. The mixture is mixed in a kneader at 60 to 120 ° C. for 5 to 30 minutes.
Kneaded for a minute, molded into a tube with an extrusion molding machine,
In the case of the roller shape, the base is fitted into the inner diameter portion, and in the case of the blade shape, the base is attached to the side surface. Then, vulcanization is performed at 120 to 200 ° C for 5 to 30 minutes, and secondary vulcanization is performed at 150 to 180 ° C for 1 to 4 hours. At this time, simultaneously with vulcanization, a foaming agent such as azodicarbonamide described above is separately charged to obtain a foamed elastic body having an average cell diameter of 150 μm or less and an Asker C hardness in the range of 20 to 60 degrees. it can. After completion of vulcanization, the removed conductive elastic body is subjected to surface polishing if necessary so as to have a desired diameter, thereby removing the skin layer. Circularity and cylindricity are given, and straightness and flatness are given when the shape is a blade.

A tube made of a flexible synthetic resin, for example, a polyethylene resin tube and having a thickness of 100 μm is brought into close contact with the surface layer of the elastic body 2 by heat shrinkage to form a coating elastic layer. The polyethylene resin tube used here has a volume resistivity of preferably 10 ⁴ to 10 ¹² Ω · cm by mixing a ceramic fine powder having an average particle diameter of 1 μm such as desired BaTiO ₃ or PbTiO ₃ -PbZrO _3. It has been adjusted to be. If it does not have heat shrinkage, the flexible synthetic resin is expanded and expanded by a vacuum plate, an internal elastic body is inserted into it, and a force to return to a natural state is constantly applied to the internal elastic body. Various other methods such as close contact can be used. On this occasion,
No adhesive was used. As described above, the heating when the flexible synthetic resin tube is brought into close contact with the internal elastic body by heating is desirably as uniform as possible, and the temperature is preferably gradually increased using an air-circulating heating furnace. The temperature range of the heat treatment is preferably in the range of 100 to 170C. When the temperature is lower than 100 ° C., the adhesion is not sufficient, and there is a material which can be thermally contracted depending on the material forming the coating elastic layer. Since the temperature of the conductive elastic body exceeds 100 ° C. due to frictional heat with the pressure contact member, the diameter of the conductive elastic body and the structure of the coating elastic layer may change during use, which is not appropriate. . Also, 17
If the temperature is higher than 0 ° C., it is not desirable because defects such as variation in surface smoothness and hardness of the coated elastic layer appear.

After the coating is completed, the conductive elastic body taken out is
Normally, the surface is polished as necessary to obtain a desired diameter, and the outer diameter, roundness, and cylindricity are determined for a roller shape, and the straightness and flatness are determined for a blade shape. Put out. However, these methods cause scratches on the surface layer of the coating elastic layer due to mechanical grinding and polishing,
As a means for obtaining the outer diameter, circularity, cylindricity, straightness, and flatness, it is desirable to apply heat to the coating elastic layer and finely adjust it. This makes it possible to simultaneously eliminate unevenness in adhesion between the coating elastic layer and the internal elastic body. Through the above steps,
A conductive elastic body having a foamed elastic body doped with ceramic fine powder on a substrate and covering the surface layer with a flexible synthetic resin also doped with ceramic fine powder was obtained.

Example 1 An experiment was conducted in which the conductive elastic body having a roller shape of the present invention obtained as described above was incorporated into an image forming apparatus shown in FIG. The results are described below. In Tables 1 to 8,
○ indicates good, △ indicates no practical problem, and × indicates that practical problem may occur depending on the use conditions. First, the thickness of the flexible synthetic resin that is the covering elastic layer,
Investigations were performed for 10 to 300 μm. Table 1 shows the results. When the thickness of the flexible synthetic resin is less than 30 μm, not only wrinkles at the time of molding are generated, but also it is not possible to have sufficient abrasion resistance, and a pinhole is generated due to charging, abnormal discharge at the time of transfer, If it exceeds 250 μm, the hardness of the conductive elastic body increases by 35 ° or more, and a conductive elastic body having a desired hardness cannot be obtained.

[0048]

[Table 1]

Further, the elongation of the flexible synthetic resin as the covering elastic layer was examined in the range of 10 to 500%. Table 2 shows the results. When the elongation is less than 10%, the coating elastic layer is cracked at the time of press contact with the opposing member, and
If it exceeds 0%, the desired surface roughness (cylindricity / flatness) cannot be obtained because the polishing property is deteriorated. Further, when the average particle size of the ceramic fine powder is 10 μm or more, the variation in the position of the electric resistance becomes large, which is not suitable for practical use.

[0050]

[Table 2]

Next, the electrical characteristics of the conductive elastic body with respect to the average particle size and the dielectric constant of the ceramic fine powder were investigated. The results are shown in Tables 3 and 4. Average particle size is 5μm
Below, the ratio of the highest resistance part to the lowest resistance part is less than 1.2 times, and if the dielectric constant is less than 100, the volume resistivity depends on the applied voltage. It was found that the volume resistivity increased rapidly with the increase. This tendency almost disappears when the dielectric constant exceeds 300. Therefore, when used for charging, phenomena and transfer means, the average particle size of the ceramic fine powder is preferably 5 μm or less and the dielectric constant is preferably 100 or more, particularly preferably 300 or more.

[0052]

[Table 3]

[0053]

[Table 4]

The overall Asker C hardness of the conductive elastic body is 5 to 8
A survey was made over a range of 0 °. Table 5 shows the results. When the Asker C hardness is less than 10 °, it is not possible to have a sufficient restoring force, and C-set occurs, and
When the angle exceeds 0 °, the facing members such as the photoreceptor are worn and deteriorated. When used as a transfer means, a sufficient nip width could be obtained in the range of 10 to 70 °.

[0055]

[Table 5]

The volume resistivity of the conductive elastic body was investigated. Table 6 shows the results. As a method of measuring the resistivity, an applied voltage of 1000 V is applied while the conductive elastic body is pressed against the photoreceptor with a force of 500 gf on one side, and plain paper is passed. The transfer current value at this time is measured. Next, the photosensitive member was replaced with an aluminum tube, and the measured transfer current value was 1
The constant current control is performed for one minute, and the voltage value after one minute is measured. The volume resistivity was calculated based on the obtained transfer current value and voltage value. 1 × 10 ⁶ Ω · cm when used as transfer means
If it is less than 1 × 10 ⁹ Ω · cm, the transfer efficiency is lowered due to excessive or insufficient transfer current or Paschen discharge, resulting in image deterioration such as toner scattering, missing characters, etc., and a good image was not obtained. . In contrast, in the case of 1 × 10 ⁶ Ω · cm or more and 1 × 10 ⁹ Ω · cm or less, good image quality could be obtained by controlling only the applied voltage.

[0057]

[Table 6]

Therefore, based on the contents of the above-mentioned examination items, the inner elastic body whose surface average cell diameter was reduced by 5% due to coating (hardness change was 4 °) and the total volume resistivity was 2 × 1
In 0 ⁸ Ω · cm conductive elastic body (NN value) (A), which surface layer the average cell diameter of the inner elastic member becomes 20% smaller by coating (hardness variation 15 °), the overall volume resistivity of 1 × 1
0 conductive elastic body ^{8 Ω} · cm (NN value) (B), in which the surface average cell diameter of the inner elastic member becomes 40% smaller by coating (hardness variation 35 °), the overall volume resistivity 7 × 10 ⁸
A comparative study was mainly performed on the conductive elastic body (C) having Ω · cm (NN value).

At first, this was set to each environment (LL: 5 ° C./20
%, NN: 20 ° C./50%, HH: 35 ° C./80%). The results obtained are shown in FIG. As a result, the volume resistivity of the conductive elastic body (A, B, C) hardly fluctuated due to the environmental fluctuation of LL to HH. Next, the voltage applied to each conductive elastic body was changed every 0.2 kV from 0.2 to 2.6 kV, and the change in volume resistivity was measured from the transfer current value flowing at that time. FIG. 10 shows the obtained results. Comparing the volume resistivity at the time of applying 600 V and 1400 V, the conductive elastic bodies (A, B,
The volume resistivity of C) hardly fluctuated (the smaller the dependence of the resistivity on the applied voltage, the better the transfer was made, regardless of the type and size of the transfer material).

The variation in the position of the electric resistance is as follows.
18, 10 m using a conductive elastic body with a length of 245 mm
A total of 32 points of a copper tape having a width of m and 4 points at equal intervals in the circumferential direction at intervals of 90 degrees, and 8 points in the longitudinal direction, and a total applied voltage of 1000 V
Was measured. FIG. 11 shows the obtained results. As a result, the volume resistivity of the conductive elastic bodies (A, B, and C) hardly varied, and the highest resistance portion was about 1.2 times the lowest resistance portion.

Next, in an experiment in which the conductive elastic body of the present invention was incorporated into an image forming apparatus, the photosensitive member of the image forming apparatus was changed to an aluminum tube, and the photosensitive body was changed to an aluminum tube in an NN environment.
After rotating continuously for 150 hours while applying a voltage of 000 V, the specific volume resistivity was measured by the same method as described above. The increase in resistivity was within 1.2 times, and it was also confirmed that the resistivity did not fluctuate with time.

From the above examination items, there was no problem in the electrical characteristics. However, the conductive elastic body of A having a small difference in the average cell diameter change width of the inner elastic body due to the presence or absence of the covering elastic layer has the internal elasticity. When incorporated into an image forming apparatus with a body surface average cell diameter of 140 μm, unevenness of the latent image and toner image occurred. In addition, the ratio of the surface average cell diameter to the deep layer average cell diameter of the internal elastic body is as large as 95%, and the coating elastic layer and the internal elastic body are not sufficiently adhered to each other, and the elasticity of the coating when pressed against a pressure-contact member such as a photoreceptor. The layer was lifted up and peeled off when continuously rotated. The conductive elastic body of C having a large difference in the surface layer average cell diameter variation width of the internal elastic body has a small average surface cell diameter of the internal elastic body up to about 60 μm, and does not cause latent image and toner image unevenness. However, the cells were compressed to the cells on the substrate side, and the hardness increased by 35 °, and the ratio of the surface average cell diameter to the deep layer average cell diameter of the internal elastic body was 75%.
In order to obtain the necessary and sufficient nip width with the pressure contact member, a total of 8 kg
The above pressure was required, and during continuous rotation, frictional degradation of the conductive elastic body and the opposing member was severely caused. In contrast,
The conductive elastic body of B having a difference in the surface cell diameter change width of the inner elastic body of 20% has a ratio of the surface average cell diameter of the inner elastic body to the deep layer average cell diameter of 75%, a hardness increase of 15 °, and an internal elastic body. The covering elastic layer adheres in a state where only the cells of the elastic body surface layer are compressed, and no lifting or peeling occurs, and the pressing member and the nip width can be obtained with an appropriate pressing force by the elastic effect of the cells on the base side, Even during continuous rotation, the conductive elastic body and the opposing member do not wear and deteriorate, and the average cell diameter of the surface layer of the internal elastic body is 100 μm.
At about m, toner image unevenness did not occur. Table 7 shows the above results.

[0063]

[Table 7]

Also, the conductive elastic layer recycled by removing the coating layer of the deteriorated conductive elastic body of the present invention and providing the coating layer on the same elastic layer again has the same performance as the new conductive elastic body. Confirmed that it can be reproduced. This makes it easy to recycle such a polymer foamed elastic body, makes it environmentally friendly, and reduces the production cost. Further, the toner is clogged on the surface of the conductive elastic body without the coating layer and cleaning is difficult. However, the conductive elastic body provided with the coating layer has good toner releasability and can be easily cleaned. Was.

Example 2 A conductive elastic body was manufactured in the same manner as in Example 1, and the inner elastic body was reduced in thickness by 15% by coating (the hardness change was 10%).
°), the overall volume resistivity is 2 × 10 ⁸ Ω · cm (NN
Value) of the conductive elastic body (A ′), the inner elastic body of which is reduced by 40% by coating (the hardness change is 30 °), and the total volume resistivity is 1 × 10 ⁸ Ω · cm (NN value). Conductive elastic body (B '), inner elastic body reduced by 3% by coating
(Hardness change is 2 °) and total volume resistivity is 7 × 10 ⁸ Ω
The comparative investigation was mainly performed on the conductive elastic body (C ′) having a cm (NN value).

First, this was used for each environment (LL: 5 ° C./20
%, NN: 20 ° C./50%, HH: 35 ° C./80%). FIG. 12 shows the obtained result. The results showed that the volume resistivity of the conductive elastic bodies (A ′, B ′, C ′) hardly fluctuated due to environmental fluctuations of LL to HH.

Next, 0.2 to 2.6 is applied to each conductive elastic body.
The applied voltage is changed every 0.2 kV up to kV, and the change in volume resistivity is measured from the transfer current value flowing at that time,
FIG. 13 shows the obtained results. The volume resistivity of the conductive elastic bodies (A ′, B ′, C ′) hardly fluctuated even when the volume resistivity at the time of application of 600 V and 1400 V was compared. (The smaller the dependency of the resistivity on the applied voltage, the better the transfer can be performed without being affected by the type and size of the transfer material.)

The position variation of the electric resistance is as follows.
18, 10 m using a conductive elastic body with a length of 245 mm
A total of 32 points of a copper tape having a width of m and 4 points at equal intervals in the circumferential direction at intervals of 90 degrees, and 8 points in the longitudinal direction, and a total applied voltage of 1000 V
Was measured. FIG. 14 shows the obtained results. As a result, the volume resistivity of the conductive elastic bodies (A ′, C ′) hardly varied and the highest resistance portion was about 1.2 times the lowest resistance portion, but B ′ Had about twice the variation.

Next, in an experiment in which the conductive elastic body of the present invention was incorporated into an image forming apparatus, the photosensitive member of the image forming apparatus was changed to an aluminum tube,
After rotating continuously for 150 hours while applying a voltage of 0 V, the specific volume resistivity was measured by the same method as described above. The increase in resistivity was within 1.2 times, and it was also confirmed that the resistivity did not fluctuate with time.

From the above examination items, in addition to the electrical characteristics, the conductive elastic body of C ′ having a small difference in the thickness change width of the internal elastic body due to the presence or absence of the covering elastic layer, can be incorporated into an image forming apparatus. And the internal elastic body was not sufficiently adhered to each other, and the elastic layer was lifted when pressed against a pressing member such as a photoreceptor, and peeled off when continuously rotated. In addition, the conductive elastic body of B ′ having a large difference in the thickness change width of the internal elastic body is compressed to the cell on the base side, and the hardness increases by 30 °, and shows the same performance as ordinary solid rubber. In order to obtain the necessary and sufficient nip width with the pressure contact member, a total of 8 kg
The above pressure was required, and during continuous rotation, frictional degradation of the conductive elastic body and the opposing member was severely caused. Excessive shrinkage of the coating layer resulted in a large variation in roller diameter, and not only required a thicker coating layer to improve this accuracy, but also caused cracks over time. On the other hand, in the case of the conductive elastic body of A ′ in which the difference in the thickness change width of the internal elastic body is 15%, the covering elastic layer adheres in a state where only the cells of the surface layer of the internal elastic body are compressed, and floating or peeling occurs. Without
The nip width with the pressing member could be obtained with an appropriate pressing force by the elastic effect of the cell on the base side, and the conductive elastic body and the opposing member did not deteriorate even during continuous rotation without variation in the roller diameter. The results are shown in Table 8.

[0071]

[Table 8]

The deteriorated conductive elastic body of the present invention can be easily peeled off since the coating layer is not fused, and the conductive elastic layer recycled by providing the coating layer on the same elastic layer again can be used. It was confirmed that performance equivalent to that of the new conductive elastic body could be reproduced. This makes it easy to recycle such a polymer foamed elastic body, makes it environmentally friendly, and reduces the production cost. Further, the toner is clogged on the surface of the conductive elastic body without the coating layer and cleaning is difficult. However, the conductive elastic body provided with the coating layer has good toner releasability and can be easily cleaned. Was.

Example 3 Vulcanization of hydrogen polysiloxane or sulfur in the presence of a foaming agent such as the above-mentioned conductive filler or azodicarbonamide in combination of one or more kinds, or a peroxide or platinum catalyst. The unvulcanized and unfoamed EPDM rubber material in which the agent is uniformly dispersed at a desired ratio is kneaded using a known rubber kneading device such as an open roll or a Banbury mixer. At this time, if necessary, additives such as a vulcanization accelerator, a softener, a plasticizer, an auxiliary, an antioxidant, and an antistatic agent can be appropriately compounded. The unvulcanized / unfoamed rubber material is formed by, for example, a method such as press molding, extrusion molding, or injection molding, and is coated on a substrate. This surface layer is coated with a fluororesin tube (PFA), and this is set in a mold having a single-cell fluororubber on the inner periphery. Then 12
0-200 ° C for 5-30 minutes, 150-180 ° C
Vulcanization / foaming / curing for 1 to 4 hours, followed by heat treatment. Thereafter, this was taken out of the mold and left at room temperature to obtain a desired roller A.

Next, a non-vulcanized / non-foamed elastic body formed of an EPDM rubber material coated with a fluororesin tube (PFA), produced in the same manner as described above, was replaced with a fluororesin tube (ETFE) containing nitrogen gas. ) And heat-treated under the above conditions. At this time, the state of the nitrogen gas is adjusted to 1320 hPa and 180 to 200 ° C. by the pressure adjusting device 90 and the temperature adjusting device 80. Thereafter, the nitrogen gas is removed from the mold and left at room temperature to obtain the target roller B. Was.

The obtained roller-shaped conductive elastic bodies A and B
In both cases, even when the internal elastic body and the coating layer were firmly adhered to each other and incorporated into an image forming apparatus or the like and were continuously rotated while being pressed against an opposing member, there was no problem such as floating or peeling of the coating layer. The variation in the position of the electric resistance of the obtained conductive elastic body is as follows. A copper tape having a width of 10 mm is provided at regular intervals at 4 points every 90 degrees in the circumferential direction and at 8 points in the longitudinal direction, for a total of 32 points.
The measurement was performed at an applied voltage of 1000 V at a point. Table 9 shows the obtained results. The portion having the highest resistance value was 1.2 times the portion having the lowest resistance value, and there was no positional variation of the resistance.

[0076]

[Table 9]

[0077]

According to the first aspect of the present invention, a single-layer conductive elastic body usually requires a high-hardness conductive elastic body to have a sufficient restoring force. Since the average cell diameter is 10% smaller than that before the coating of the coating elastic layer, it is possible to have a sufficient restoring force in the deep part of the internal elastic body, so that the hardness is relatively low and the single elastic body has a relatively low hardness. It is possible to obtain a conductive elastic body having the same restoring force as the layer conductive elastic body. Since the surface cell diameter of the inner elastic body becomes smaller and the conductivity of the adhesive surface with the covering elastic layer becomes smoother, it is possible to suppress image quality deterioration such as uneven density of the latent image and toner image due to the cell diameter. . In addition, when there is no covering elastic layer, it is very difficult to obtain roundness and cylindricity when the internal elastic body is in the form of a roller, straightness and flatness when the internal elastic body is in the form of a blade. By covering the surface layer of the internal elastic body with the covering elastic layer, it is possible to obtain more accurate roundness, cylindricity, straightness, and flatness.

According to the second aspect of the present invention, a single-layer conductive elastic body usually needs a high-hardness conductive elastic body to have a sufficient restoring force, but is composed of a base and an internal elastic body. By covering the surface layer of the conductive elastic body with the covering elastic layer, the thickness of the inner elastic body is reduced by 5 to 20% as compared with before the covering elastic layer is coated, so that the initial and the initial thickness of the covering elastic layer can be reduced. It is possible to obtain a conductive elastic body having relatively low hardness and a restoring force equivalent to that of a single-layer conductive elastic body without causing performance deterioration such as cracking with time. Further, when there is no covering elastic layer, when the internal elastic body is thinner by 20% or more, roundness and cylindricity are obtained when the internal elastic body is roller-shaped, and straightness and flatness are obtained when the internal elastic body is blade-shaped. It is very difficult to achieve more precise roundness, cylindricity, straightness, and flatness by coating the surface layer of the base and the inner elastic body with a coating elastic layer and making it 5 to 20% thinner. Becomes possible.

According to a third aspect of the present invention, the inner elastic body after coating with the coating elastic layer has a surface layer average cell diameter of 90% or less of the deep layer average cell diameter, so that the inner elastic body has a deep layer portion. Since it is possible to have a sufficient restoring force, it is possible to obtain a conductive elastic body having relatively low hardness and a restoring force equivalent to that of a single-layer conductive elastic body. In addition, since the surface cell diameter of the inner elastic body becomes smaller and the conductivity of the adhesive surface with the coating elastic layer becomes smoother, it is possible to suppress image quality deterioration such as uneven density of latent images and toner images due to cell diameter. Becomes

According to a fourth aspect of the present invention, the latent image due to a change in the resistance value at the joint surface between the internal elastic body and the coating elastic layer is provided because the surface cell diameter of the internal elastic body after the coating of the coating elastic layer is 100 μm or less. And unevenness of the toner image can be suppressed.

According to the fifth aspect of the present invention, a single-layer conductive elastic body usually needs a high hardness conductive elastic body to have a sufficient restoring force. By covering the elastic layer and increasing the hardness by 5 to 30 °,
It is possible to obtain a conductive elastic body having relatively low hardness and a restoring force equivalent to that of a single-layer conductive elastic body. In addition, when there is no covering elastic layer, it is very difficult to obtain roundness and cylindricity when the internal elastic body is in the form of a roller, straightness and flatness when the internal elastic body is in the form of a blade. By covering the surface layer of the internal elastic body with the covering elastic layer, it is possible to obtain more accurate roundness, cylindricity, straightness, and flatness.

According to a sixth aspect of the present invention, when the hardness of the conductive elastic body is 10 to 70 °, abrasion due to friction with the press-contact member can be suppressed. The nip width formed when the body is brought into contact with the pressure contact member can be sufficiently secured, stable image quality can be obtained, and stable transfer of the transfer material can be performed.

According to a seventh aspect of the present invention, as the means for adhering the covering elastic layer to the surface layer of the internal elastic body, the covering elastic layer is brought into close contact by heat shrinking.
At the time of recycling, the coating elastic layer can be easily peeled off, and the internal elastic body can be reused as it is, which is environmentally friendly and reduces costs. Further, since the adhesive is not used, the adhesive does not exude to the surface of the conductive elastic body, so that it is possible to prevent an adverse effect on the volume resistivity of the entire rubber roller.

According to the eighth aspect of the present invention, when the temperature for thermally shrinking the coated elastic layer is 100 ° C. or higher, the coated elastic layer can be sufficiently adhered to the internal elastic body. Even when the temperature is lower than 100 ° C., there is a material which can be thermally contracted depending on the material forming the coating elastic layer. In this case, when used in an actual machine, the use environment (especially around 40 ° C.) and the frictional heat with the pressure contact member The temperature of the conductive elastic body is 100 ° C.
Therefore, the diameter of the conductive elastic body and the composition of the coating elastic layer may change during use, which is not appropriate.

According to a ninth aspect of the present invention, as the means for bringing the covering elastic body into close contact with the surface layer of the internal elastic body, a force for extending the covering elastic layer and returning to a natural state is always applied to the internal elastic body. As a result, the material of the internal elastic body deteriorates severely at high temperatures,
Even when close contact by heat shrinkage is not possible, close contact can be achieved without using an adhesive. Further, the coating elastic layer can be easily peeled off at the time of recycling, and the internal elastic layer can be reused as it is, which is environmentally friendly and reduces costs. Also, since the adhesive is not used, the adhesive does not exude to the surface of the conductive elastic body,
An adverse effect on the volume resistivity of the entire rubber roller can be prevented.

According to a tenth aspect of the present invention, the roundness, cylindricity, straightness, and flatness are adjusted by means of applying heat to the coating elastic layer to finely adjust the roundness, cylindricity, straightness, and flatness. By finely adjusting, it is possible to suppress the insufficient variation in the close contact position depending on the position more naturally and more precisely than finely adjusting mechanically.

According to the eleventh aspect of the present invention, since the coating elastic layer is made of a flexible synthetic resin, the conductive elastic body is deteriorated by abrasion load with the opposing member, and the composition of the base rubber is changed. Changes in the volume resistivity of the conductive elastic body due to contamination, prevention of oxidation of the surface of the internal elastic body due to dielectric breakdown, prevention of problems such as contamination of the opposing member by the conductive elastic body, and improvement of toner releasability By doing so, cleaning becomes easy, and a long life can be realized by increasing the strength of the conductive elastic body. Further, since the flexible synthetic resin can be easily peeled off, the internal elastic body can be reused as it is, which is environmentally friendly and reduces costs.

According to a twelfth aspect of the present invention, the coating elastic layer has an elongation of 10 to 500%, and the coating elastic layer is formed when the internal elastic body has a low hardness when the elongation is less than 10%. It is possible to eliminate defects such as cracks in the layer and poor polishing properties when the layer thickness exceeds 500%, so that a desired surface roughness cannot be obtained, and a positional variation in electric resistance increases.

According to a thirteenth aspect, the flexible synthetic resin forming the covering elastic layer has a thickness of 30 μm to 250 μm.
By being μm, wrinkles and charging during molding, pinholes due to abnormal discharge and the like during transfer can be prevented, and the appropriate hardness and volume resistivity of the conductive elastic body,
The wear resistance can be maintained.

According to the fourteenth aspect of the present invention, since the substrate of the flexible synthetic resin forming the covering elastic layer is a non-polar polymer resin, the volume resistivity does not fluctuate due to an environmental change. It is possible to obtain a conductive elastic body. Also, since the flexible synthetic resin can be easily peeled off,
The internal elastic body can be reused as it is, which is environmentally friendly and reduces costs.

According to a fifteenth aspect of the present invention, since the substrate of the flexible synthetic resin forming the covering elastic layer is polyethylene, the covering elastic layer itself does not cause a change in volume resistivity due to an environmental change. Therefore, it is possible to suppress a change in volume resistivity due to a change in the environment of the conductive elastic body as a whole. It has excellent ozone resistance and not only increases the strength of the conductive elastic body, but also improves the releasability of the toner, improves the cleaning performance, and prevents the toner from entering the cells on the conductive elastic body surface. In addition, an increase in the volume resistivity of the conductive elastic body can be prevented. Further, since the flexible synthetic resin can be easily peeled off, the internal elastic body can be reused as it is, which is environmentally friendly and reduces costs.

According to a sixteenth aspect of the present invention, when the internal elastic body is a foamed elastic body, when the internal elastic body is in pressure contact with the opposing member, wear of the opposing member due to friction with the opposing member is suppressed. By providing a width, it is possible to further facilitate paper conveyance.

According to a seventeenth aspect of the present invention, since the substrate forming the foamed elastic body is a non-polar rubber, the substrate forming the foamed elastic body itself may cause a change in volume resistivity due to an environmental change. Since there is no, it is possible to obtain a conductive elastic body that hardly causes a change in volume resistivity due to environmental changes by selecting a conductive filler to be mixed to add conductivity to the foamed elastic body. Becomes When used in the transfer unit, if there is no change in resistivity due to an environmental change, there is no need to detect each environmental condition and change the transfer bias according to the detected environment.

According to the eighteenth aspect of the present invention, since the nonpolar rubber is formed from at least ethylene-propylene-diene copolymer rubber (EPDM), EPDM itself may cause a change in volume resistivity due to an environmental change. Since there is no, it is possible to obtain a conductive elastic body that hardly causes a change in volume resistivity due to environmental changes by selecting a conductive filler to be mixed to add conductivity to the foamed elastic body. Becomes When used for transfer means,
If the resistivity does not fluctuate due to the environmental change, it is not necessary to detect each environmental condition and change the transfer bias according to the detected environment. EPDM is relatively chemically stable and inexpensive, so that it can be easily used.

The invention according to claim 19 is characterized in that the conductive filler is made of a ceramic fine powder obtained by pulverizing a polycrystalline sintered body sintered at a chemically stable high temperature, so that the coating layer and The internal elastic body or its raw material and other mixed substances do not easily undergo a chemical change, and there is no need to select the presence or absence of the polarity of the polymer constituting the coating layer and the internal elastic body and the heating temperature in the manufacturing process. . In addition, since the particle size can be reduced, there is no occurrence of positional variation due to the distribution state of the conductive filler or variation of the volume resistivity due to the applied voltage.

According to a twentieth aspect of the present invention, when the ceramic fine powder has a dielectric constant of 100 or more, when a voltage is applied to the conductive elastic body, the ceramic fine powder is charged without being charged. Since the current gradually increases with an increase in the voltage, it is possible to suppress a change in the volume resistivity due to the applied voltage. Further, it is possible to prevent a change in electric resistance during continuous energization.

According to a twenty-first aspect of the present invention, a fine powder of a polycrystalline sintered body composed of at least two compounds is used as the fine ceramic powder, so that a fine powder of a sintered body composed of one kind of compound is obtained. Is also more chemically stable,
Select the presence or absence of polarity of the polymer constituting the coating layer and the internal elastic body and the heating temperature in the manufacturing process without causing a chemical change with the coating layer and the internal elastic body or its raw material and other mixed substances. Nor. Also, the price is relatively low.

According to a twenty-second aspect of the present invention, a polycrystalline sintered compact fine powder comprising at least two compounds contains at least titanium oxide to have a dielectric constant of 300.
In many cases, the above-mentioned sintered body fine powder is obtained, and it is possible to provide a conductive filler which is easy to manufacture, inexpensive and environmentally friendly.

According to the twenty-third aspect of the present invention, when the average particle size of the ceramic fine powder is 5 μm or less, the same dispersed state as when an ionic conductive filler is used can be realized. It is possible to obtain a conductive elastic body which does not cause a variation in resistance position.

According to a twenty-fourth aspect of the present invention, when the conductive elastic body has a volume specific resistivity of 10 ⁶ to 10 ⁹ Ω · cm, it can be used in any transfer material when used as a transfer means. And good transfer performance can be obtained.

According to the twenty-fifth aspect of the present invention, since the conductive elastic body is in the form of an endless roller, when it is used as a transfer roller, for example, it can be easily brought into contact with an opposing member (OPC) and sufficient for transfer. Thus, a high nip width can be obtained and a high-quality image can be obtained. Further, since the opposing member (OPC) and the transfer roller press the transfer material against each other, it is possible to realize appropriate conveyance of the transfer material.

According to the twenty-sixth aspect of the present invention, when the conductive elastic body is in the form of a flat blade, for example, when used as a transfer blade, the conductive elastic body has a smaller size than a transfer roller.
The toner is less scattered in the upstream portion of the transfer portion, and the nip width equivalent to that of the opposing member (OPC) is obtained. The conductive elastic body has a small volume, is simple in configuration, and does not require any special manufacturing technology. It can be manufactured at low cost.

According to the twenty-seventh aspect of the present invention, since the conductive elastic body is in the form of an endless belt, high image quality can be realized due to the merit of a large nip width when used as a transfer belt, for example. In the case of a color image, it is possible to use a tandem method which has a higher process speed than the multiple transfer method. Further, since the transfer material is transported together with the transfer belt, it is possible to realize appropriate transport of the transfer material.

According to the twenty-eighth aspect of the present invention, the conductive elastic body is used as a means for charging, developing and transferring, thereby preventing abrasion deterioration of the conductive elastic body itself and an opposing member in contact with the conductive elastic body. Also, since the size accuracy of the conductive elastic body is high, the conductive elastic body does not become eccentric,
Not only can the long life of the machine be realized, but also the volume resistivity of the conductive elastic body does not fluctuate due to environmental changes, so that an expensive power supply for changing the applied voltage and the like is not required, leading to a reduction in the cost of the machine. Furthermore, it is excellent in ozone resistance, not only increases the strength of the conductive elastic body, but also improves the releasability of the toner, improves the cleaning property, and prevents the toner from entering the cells on the surface of the conductive elastic body. This makes it possible to prevent the volume resistivity of the conductive elastic body from increasing. Therefore, an image excellent in quality can be obtained. Further, since the flexible synthetic resin can be easily peeled off, the internal elastic body can be reused as it is, which is environmentally friendly and reduces costs.

According to the twenty-ninth aspect of the present invention, the expansion force generated due to the expansion and hardening of the unfoamed elastic body is used as the force due to the expansion of the internal elastic body, and the covering layer and the internal elastic body are brought into close contact with each other. Compared to the conventional coating method (using the heat shrinkage of the coating layer, extending the coating layer, coating by spraying or coating, etc.), the coating layer does not expand or contract unnecessarily, so the resistance of the coating layer It is possible to obtain a conductive elastic body that does not cause unevenness in value. Also,
The process which has been performed in a separate process so far can simultaneously perform the molding of the internal elastic body and the coating of the coating layer, thereby reducing the manufacturing time and cost, and also conserving energy.

According to the thirtieth aspect, by applying a force from the outer periphery of the coating layer in addition to the force due to the expansion of the internal elastic body, the local force due to the excessive expansion of the coating layer due to the expansion of the internal elastic body is obtained. Variations can be suppressed, and the shape of the obtained conductive elastic body can be adjusted. In addition, it is possible to strengthen the adhesion between the coating layer and the internal elastic body.

According to the thirty-first aspect of the present invention, by uniformly applying a force from the outer periphery of the coating layer by utilizing the expansion of the gas, the spatial expansion of the coating layer due to the expansion of the internal elastic body causes a local expansion. Variation in force can be suppressed, and the shape of the obtained conductive elastic body can be adjusted. In addition, it is possible to strengthen the adhesion between the coating layer and the internal elastic body.
Since gas is used, the operation of temperature, volume, and pressure can be easily performed, so that the load operation on the coating layer can be performed.

According to the thirty-second aspect of the present invention, the force from the outer periphery of the coating layer is easily applied by uniformly applying the force from the outer periphery of the coating layer by causing the gas to expand in volume due to the temperature rise of the gas. Can be obtained. Further, by controlling the temperature, it is possible to suppress the force from the outer periphery of the coating layer.

According to the thirty-third aspect of the present invention, by providing a means for releasing pressure more than necessary, it is possible to prevent the internal elastic body from being reduced by excessive pressure so as not to hinder the close contact with the coating layer. Becomes possible. It also prevents damage to the device due to excessive rise in pressure.

According to the thirty-fourth aspect of the present invention, a temperature sensor is provided as a means for detecting the temperature of the gas.
The temperature of the gas can be adjusted, and adjustment for obtaining a necessary and sufficient force for the close contact between the coating layer and the internal elastic body can be performed.

According to the thirty-fifth aspect of the present invention, a pressure sensor is provided as a means for detecting the pressure of a gas.
The pressure of the gas can be adjusted, and adjustment for obtaining a necessary and sufficient force for the close contact between the coating layer and the internal elastic body can be performed.

According to a thirty-sixth aspect of the present invention, the use of a fluorine-based tube as the material containing the gas to be expanded provides excellent releasability, so that the conductive elastic body can be formed without adhering to the coating layer. Can be obtained.

According to the thirty-seventh aspect of the present invention, by using a nitrogen gas or an argon gas as the gas to be expanded, a chemical change or a state change such as an unexpected combustion due to a change in temperature, pressure, or volume does not occur. It can be used safely.

According to the thirty-eighth aspect of the present invention, the force from the outer periphery of the coating layer is uniformly applied by utilizing the expansion of the elastic body, so that the covering layer is excessively expanded due to the expansion of the internal elastic body. It is possible to suppress a variation in force and to adjust the shape of the obtained conductive elastic body. In addition, it is possible to strengthen the adhesion between the coating layer and the internal elastic body. Since the elastic body is used, there is no problem such as extreme expansion, so that an advanced control system is not required.

According to the thirty-ninth aspect of the present invention, since the elastic body to be expanded is a foamed elastic body, it can be expanded more stably than a solid elastic body, so that a pressure can be uniformly applied to the coating layer. It is possible to do.

According to the forty-ninth aspect of the present invention, since the expanded elastic body is made of a single cell, not only the polymer base material constituting the elastic body but also the gas contained in the single cell can be expanded. Therefore, it is possible to expand more stably.

Since the elastic body to be expanded is a fluorine-based elastic body and does not adhere to the coating layer, the invention according to claim 41 is suitable for reuse of the elastic body.

The invention according to claim 42, when carried out in a mold, allows not only foaming and curing of the internal elastic body and coating of the coating layer at the same time, but also molding. It is also possible to simultaneously heat the internal elastic body and the gas or elastic body on the outer periphery of the coating layer.

According to the invention of claim 43, the elastic body and the gas to be expanded are integrated into the mold, so that the elastic body can be reused. In mass production of the conductive elastic body, even a small amount of the elastic body becomes a considerable amount, which is an effective means in terms of effective use of resources and cost.

In the invention according to claim 44, in the case of a gas, it is desirable that the gas does not cause a chemical change with the coating layer.
In the case of an elastic body, it is necessary that the elastic body and the coating layer do not adhere to each other. Therefore, a fluorine-based elastic body is most desirable as a material having both properties.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a roller-shaped conductive elastic body according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a roller-shaped conductive elastic body of one embodiment of the rubber roller of the present invention.

FIG. 3 is a cross-sectional view showing a schematic configuration of a blade-shaped conductive elastic body according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a schematic configuration of a roller-shaped conductive elastic body according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a schematic configuration of a blade-shaped conductive elastic body according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a schematic configuration of an embodiment of an apparatus for performing the method of the present invention.

FIG. 7 is a sectional view showing a schematic configuration of another embodiment of an apparatus for performing the method of the present invention.

FIG. 8 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus as an application example of the conductive elastic body of the present invention.

FIG. 9 is a graph showing the variation of the volume resistivity of the present invention and the comparative conductive elastic body in each environment.

FIG. 10 is a graph showing the applied voltage dependence of the volume resistivity of the present invention and the comparative conductive elastic body.

FIG. 11 is a graph showing the position variation of the electric resistance of the present invention and the comparative conductive elastic body.

FIG. 12 is a graph showing a change in a volume resistivity value of the present invention and a comparative conductive elastic body in each environment.

FIG. 13 is a graph showing the applied voltage dependence of the volume resistivity of the present invention and the comparative conductive elastic body.

FIG. 14 is a graph showing the position variation of the electric resistance of the present invention and the comparative conductive elastic body.

[Explanation of symbols]

 1: base 2: internal elastic body 3: coated elastic layer 4: conductive filler 5: cell 6: mold 7: foamed elastic body 8: gas 9: tube 10: image forming section 11: photosensitive drum 18: charging Roller 21: Developing roller 23: Transfer roller

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B32B 7/02 104 B32B 7/02 104 4F100 25/14 25/14 4F213 27/32 27/32 Z 4J002 F16C 13/00 F16C 13/00 ABE G03G 15/02 101 G03G 15/02 101 15/08 501 15/08 501D 15/16 103 15/16 103 H01B 1/20 H01B 1 / 20Z // C08J 9/04 CEQ C08J 9/04 CEQ C08K 3/20 C08K 3/20 C08L 101/00 C08L 101/00 B29K 21:00 B29K 21:00 23:00 23:00 27:12 27:12 C08L 21:00 C08L 21:00 (72 Inventor Kohei Kamei 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Japan, Sharp Corporation (72) Inventor Hideki Onishi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Shiro Wakahara 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside Sharp Corporation Terms (reference) 2H003 AA18 BB11 CC05 2H032 AA05 BA23 2H077 AD06 AD07 AD13 AD23 EA15 FA11 FA22 FA25 3J103 AA02 AA14 AA51 BA41 EA05 FA15 GA02 GA03 GA52 GA57 GA58 GA74 HA03 HA12 HA18 HA20 HA22 HA31 HA41 HA41 AA14A07 A04 CA22 CC04Y CC06Y CD06 CE02 CE17 CE43 CE86 CE94 DA03 DA09 DA47 4F100 AD00B AD00C AD00H AK04C AK12 AK75B AN00B AR00C AT00A BA03 BA10A BA10C BA41 CA21B CA21C DA11 DJ01B EJ022 EJ212 GB48 JA03C JA11B JA11C JA11H JG01B JG01C JG04B JG04C JG05B JG05C JG05H JK01C JK06 JK07B JK07C JK08C JK12B JK17C YY00B YY00C 4F213 AA04 AA04E AA09 AA11E AA45 AA46E AB16 AB23 AC03 AG16 AH04 WA18 WA43 WA52 WA63 WA72 WA87 WB01 WB13 WB22 WC03 WE02 WE06 WE07 WE16 WF06 WF37 WK1 AC02 WW1 ACB BB011 BC051 BC061 BC071 BC091 BC111 BD041 BD121 BE061 BG041 BG062 BG101 BH021 BJ002 BK001 BM002 CC031 CC101 CD001 CE001 CF001 CG001 CH041 CK021 CL001 CM012 CP031 DA016 DA036 DA086 DA096 DC006 D E006 DE076 DE096 DE136 DE146 DE186 DE196 DG046 DJ006 DJ016 DJ056 EN136 EV256 EW046 FA066 FA086 FB076 FB266 FD112 FD116 FD140 FD150

Claims (44)

[Claims] 1. A conductive elastic body comprising at least a base and two or more elastic bodies, wherein a covering elastic layer is coated on a surface layer of a conductive elastic body comprising a base and an internal elastic body. A conductive elastic body, wherein the average cell diameter of the surface layer of the internal elastic body is smaller by 10% or more than before the coating of the coating elastic layer. 2. A conductive elastic body comprising at least a base and two or more layers of elastic bodies, wherein a covering elastic body is coated on a surface layer of a conductive elastic body composed of a base and an internal elastic body. A conductive elastic body, wherein the thickness of the internal elastic body is reduced by 5 to 20% as compared to before the coating of the covering elastic layer. 3. The conductive elastic body according to claim 1, wherein a surface layer average cell diameter of the internal elastic body after coating the coating elastic layer is 90% or less of a deep layer average cell diameter. 4. The conductive elastic body according to claim 1, wherein the surface cell diameter of the internal elastic body after covering with the covering elastic layer is 100 μm or less. 5. The conductive elastic body according to claim 1, wherein the hardness of the internal elastic body is higher in the range of 5 ° to 30 ° than before the coating of the covering elastic layer. 6. The conductive elastic body according to claim 1, wherein a hardness of the conductive elastic body composed of at least two or more elastic bodies is 10 to 70 °. 7. The conductive elastic body according to claim 1, wherein the means for bringing the covering elastic layer into close contact with the surface layer of the internal elastic body is brought into close contact by thermally shrinking the covering elastic layer. 8. The temperature for thermally shrinking the coated elastic layer is 10
The conductive elastic body according to claim 7, wherein the temperature is 0C or higher. 9. As means for bringing the covering elastic body into close contact with the surface layer of the inner elastic body, the covering elastic layer is stretched, and a force for returning to a natural state is constantly applied to the inner elastic body so as to make close contact. The conductive elastic body according to claim 1. 10. A means for applying heat to the coated elastic layer to finely adjust the roundness, cylindricity, straightness, and flatness to obtain a roundness,
3. The conductive elastic body according to claim 1, wherein cylindricity, straightness, and flatness are finely adjusted. 11. The conductive elastic body according to claim 1, wherein the covering elastic layer is a flexible synthetic resin. 12. The coated elastic layer has an elongation of 10 to 500%.
The conductive elastic body according to claim 1, wherein: 13. The coating elastic layer has a thickness of 30 μm to 250 μm.
The conductive elastic body according to claim 1, wherein the conductive elastic body has a thickness of μm. 14. The conductive elastic body according to claim 11, wherein the flexible synthetic resin is a non-polar polymer resin. 15. The conductive elastic body according to claim 14, wherein the nonpolar polymer resin is polyethylene. 16. The conductive elastic body according to claim 1, wherein the internal elastic body is a foamed elastic body. 17. The conductive elastic body according to claim 16, wherein the substrate forming the foamed elastic body is a nonpolar rubber. 18. The non-polar rubber is at least ethylene-
The conductive elastic body according to claim 17, wherein the conductive elastic body is formed from propylene-diene copolymer rubber (EPDM). 19. A ceramic fine powder obtained by pulverizing a polycrystalline sintered body sintered at least at a high temperature is mixed as a conductive filler in order to add conductivity to the coating elastic layer and the internal elastic body. The conductive elastic body according to claim 1, wherein the conductive elastic body comprises: 20. A ceramic fine powder having a dielectric constant of 100.
20. The conductive elastic body according to claim 19, wherein: 21. The conductive elastic body according to claim 19, wherein a fine polycrystalline sintered body powder composed of at least two or more compounds is used as the ceramic fine powder. 22. The conductive elastic body according to claim 21, wherein at least one of the polycrystalline sintered compact fine powders comprising at least two or more compounds contains titanium oxide. 23. The conductive elastic body according to claim 19, wherein the ceramic fine powder has an average particle size of 5 μm or less. 24. The conductive elastic body has a volume specific resistivity of 10
20. The conductive elastic body according to claim 19, wherein the elastic modulus is ⁶ to 10 < ⁹ > [Omega] .cm. 25. The conductive elastic body according to claim 1, wherein the conductive elastic body has an endless roller shape. 26. The conductive elastic body according to claim 1, wherein the conductive elastic body has a shape of a flat blade. 27. The conductive elastic body according to claim 1, wherein the conductive elastic body has an endless belt shape. 28. A charging means for contact-charging at least the surface of the image carrier with the conductive elastic body according to claim 1 or 2, supplying toner to an electrostatic latent image formed on the surface of the image carrier. One of a developing means for developing a visible image and a transfer means for transferring a toner image formed on the image carrier to a recording medium.
An image forming apparatus comprising: a plurality of image forming apparatuses; 29. A method for producing a conductive elastic body composed of at least two or more layers of elastic bodies, wherein an expansion force generated by foaming and hardening of an unfoamed elastic body is used as a force due to expansion of the internal elastic body, A method for producing a conductive elastic body, comprising bringing a coating layer and an internal elastic body into close contact with each other. 30. The manufacturing method according to claim 29, wherein the coating layer and the internal elastic body are brought into close contact with each other by applying a force from the outer periphery of the coating layer in addition to the force due to the expansion of the internal elastic body. Method. 31. The manufacturing method according to claim 30, wherein the coating layer and the internal elastic body are brought into close contact with each other by uniformly applying a force from the outer periphery of the coating layer by utilizing gas expansion. Method. 32. The coating layer and the internal elastic body are brought into close contact with each other by causing a volume expansion of the gas due to a rise in the temperature of the gas and uniformly applying a force from the outer periphery of the coating layer. Item 32. The production method according to Item 31, 33. The manufacturing method according to claim 32, wherein, when the volume expansion of the gas is caused by the rise in the temperature of the gas, means for releasing pressure more than necessary is used. 34. The method according to claim 31, wherein a temperature sensor is used as a means for detecting the temperature of the gas. 35. The method according to claim 31, wherein a pressure sensor is used as a means for detecting the pressure of the gas. 36. The method according to claim 31, wherein a fluorine-containing tube is used as the material containing the gas to be expanded. 37. The method according to claim 31, wherein nitrogen gas or argon gas is used as the gas to be expanded.
The production method described in 1. 38. The manufacturing method according to claim 30, wherein the coating layer and the internal elastic body are brought into close contact with each other by uniformly applying a force from the outer periphery of the coating layer using the expansion of the elastic body. Method. 39. The method according to claim 38, wherein the elastic body to be expanded is a foamed elastic body. 40. The method according to claim 39, wherein the expanded elastic body is made of a single cell. 41. The manufacturing apparatus according to claim 38, wherein the elastic body to be expanded is a fluorine-based elastic body. 42. The method according to claim 29, wherein the method is carried out in a mold. 43. The manufacturing method according to claim 29, wherein an apparatus is used in which the elastic body and the gas to be expanded are integrated in the mold and can be reused. 44. The method according to claim 29, wherein the coating layer adhered to the internal elastic body is a fluorine-based elastic body.